The invention relates to a cleaning device and to a method for washware. This cleaning device may be, in particular, a conveyor dishwasher, in particular for commercial use, for example in facilities for mass catering, such as, in particular, office canteens, canteens in schools, public authorities, hospitals or care facilities. The cleaning device and the method can be used, in particular, to clean washware in the form of items to be washed in a dishwasher which are used directly or indirectly for preparing, storing or serving food and drinks. Said items to be washed in a dishwasher may be, in particular, dishes and/or trays. Other fields of use of the present disclosure are also feasible in principle.
The prior art discloses a large number of cleaning devices. In this respect, reference is made in the text which follows, in particular, to dishwashers, without limiting further possible refinements of this disclosure. In addition to single-chamber dishwashers, so-called conveyor dishwashers in which the washware is transported through one or more cleaning chambers by means of a transportation device are also known. Conveyor dishwashers of this kind have, for example, different treatment zones or cleaning zones for the washware. Therefore, at least one wash zone for main cleaning of the washware and also at least one downstream final-rinse zone are present in many cases. At least one fresh-water final-rinse system (FWFRS) is generally provided in the final-rinse zone. In the fresh-water final-rinse system, fresh water, which can optionally be heated and/or admixed with a final-rinse aid, in particular in the form of so-called final-rinse solution, is applied to the washware by means of at least one nozzle. The fresh-water final-rinse system is generally used to rinse off the final residues of dirt and residues of wash liquid from the washware, in order to achieve a satisfactory dishwashing result.
A plurality of nozzles are generally used in the fresh-water final-rinse zone in order to apply the final-rinse solution to the washware. These nozzles are usually inserted into at least one pipe which is arranged in the fresh-water final-rinse zone transverse, for example orthogonal, to the transportation direction.
Depending, for example, on a passage width of the conveyor dishwasher, a specific number of nozzles is generally required in order to generate a desired spray pattern. This spray pattern should be enough to wet the washware over the entire passage width in as uniform a manner as possible. If too few nozzles are used, gaps in the film of the cleaning fluid on the washware may result for example. In addition, a nozzle generally requires a minimum quantity of final-rinse fluid per unit time in order to form a good spray pattern. Falling below this quantity generally leads to a poor spray pattern with the washware consequently being wetted in a non-uniform manner.
Conveyor dishwashers are described, for example, in DE 10 2004 046 758 A1, DE 10 2007 053 381 B3, DE 10 2009 035 668 A1 or in the German patent application bearing the number DE 10 2011 077 660 which was published after this application. A large number of conveyor dishwashers have two rinsing pipes in the final-rinse zone, wherein one of these rinsing pipes is arranged above the transportation device and one is arranged below the transportation device. These rinsing pipes can each have, for example, six uniformly distributed nozzles, so that the washware is rinsed off from above and from below. The rinsing-off effect is generally uniform over the entire passage width, that is to say the maximum loadable width of the transportation device perpendicular to the transportation direction. For example, conventional conveyor dishwashers can have a width of 500 mm, 750 mm, 1000 mm or even 1200 mm. Depending on the passage width, the rinsing pipes of the fresh-water final-rinse zone, also called nozzle pipes, can be designed to be longer or shorter for example, and the number of nozzles in these nozzle pipes can be selected in accordance with this.
The number of nozzles, the size of the nozzles (for example the opening cross section of said nozzles) and/or a pressure in the fresh-water final-rinse system can have a strong influence on the throughput of final-rinse fluid and therefore the consumption, for example, of fresh water. However, the total consumption of fresh water has a significant influence on the consumption of resources by the conveyor dishwasher. Fresh water generally has to be heated, for example to an operating temperature of between 80° C. and 100° C., for example to from 85° C.-90° C. Furthermore, final-rinse aid and/or cleaning agent generally have/has to be added in a metered fashion to the final-rinse fluid depending on the quantity of fresh water flowing in.
However, phases and/or periods of time in which a small amount of washware is produced repeatedly occur during operation of the conveyor dishwasher. In these phases, there may be areas on the transportation device, for example on a conveyor belt, in which there is no washware. As an alternative, for example in the case of a rack conveyor dishwasher in which racks holding the washware are transported through the conveyor dishwasher, these racks may be only partially loaded with washware, or the transportation device may be only incompletely populated by conveyor racks.
The prior art discloses, in principle, devices with the aid of which it is possible to identify whether there is washware in the transportation device or not. Depending on how the transportation device is populated by washware, individual cleaning zones of the dishwasher can then be switched on and switched off in accordance with the progress of the washware. The operation of the fresh-water final-rinse zone can also be influenced in such a way. Fresh water can be saved in this way.
AT 254453 discloses a dishwasher which has a conveyor belt for conveying dishes through a wash zone and a rinse zone. Dishes are detected by means of a photocell control means and switching on and switching off of rinse water is controlled.
DE 1 968 268 discloses a dishwasher with regulation of dishwashing water, in which dishes are routed past a washing and rinsing device by means of a conveyor belt. A pivotable grid is provided upstream of a dishwashing zone in a movement region of the dishes for switching on and switching off dishwashing water. The grid which is moved by the dishes immediately switches on the dishwashing water in the event of a forward movement and switches off the dishwashing water in the event of reversal.
DE 1 963 534 U discloses a rinsing device for dishwashers with continuous or intermittent transportation of dishes. Said rinsing device has a momentary-contact switch which is mounted such that it swings. As dishes pass through, an electrical circuit to a magnetic valve is closed and passage of water is enabled for as long as dishes which are passing through hold the momentary-contact switch in an inclined position.
In spite of the advantages achieved by the known devices, in particular in respect of saving resources, further potential for optimization exists, in particular in the case of commercial dishwashers. In this case, it should be noted, in particular, that when the transportation device is not completely populated with washware as before, final-rinse fluid is unnecessarily sprinkled into empty belt regions and, as a result, fresh water in particular is consumed.